JPS6024426B2 - Non-conductive polar gas detection method and detection element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gaseous product detection method and an environmental composition detection element.

Conventional combustion detectors respond to combustion characteristic sensors such as exothermic type, combustion flame type, photoelectric type, ionization chamber type, metal oxide or polymeric organic semiconductor type, electrolytic cell type, etc.

Hontsubaki green acid scale horse mackerel - to overcome the enemy, and has virtually no dipole-hydrogen bonding force (5.0 ergs/earth or less, preferably 1 erg/or less) Highly sensitive It has already developed a non-conductive sensor.

It is desirable that the surface resistivity be greater than 1 x 1 and 5 ohms per ground, and that the volume resistivity be greater than 1 x 1 and 5 ohms per touch at 50% relative humidity (50% R.day). Promising polymeric materials include polytetrafluoroethylene (TFE), barfluoroalkoxy (PFA), materials sold under the trade name Teflon such as fluorinated ethylene-propylene (FEP), polystyrene, and polyethylene.

These materials absorb polar gas molecules generated by combustion, creating a detectable induced charge. The probe or electrode also senses ionic groups and charged particles caused by combustion products when they approach the surface. The present invention provides a non-conductive sensor that includes an electrical dipole and/or monopole placed in a special charge state to create a charge-enhancing electric field.

The electric field in this case makes it possible to align dipoles or charges that accumulate on the surface of the material or preferably within it. Useful materials include polytetrafluoroethylene (Teflon TFE), perf. loalkoxy resin (Teflon PFA), fluorinated ethylene propylene copolymer (FE
P), polystyrene, polyethylene, etc. The high volume and surface resistivities of these materials play an important role in retaining the fin load over long periods of time. The water absorption and water adsorption properties of these materials are low.
These non-conductive materials can be charged by any suitable technique. The electrical response to combustion products follows the initial pulse with a unique ramp response function increase that does not occur with uncharged, non-conducting adsorptive sensor materials.

In one preferred embodiment, the conductive substrate has a support and a connecting bolt on its back side and is integrated into this substrate and mounted within a suitable external conductor which serves as a shield earth to form the probe. .

A method is being explored in which the external conductor is separated from the probe so that the probe functions as an adsorption detection element. In another example, the outer conductor and shield ground may be placed in close proximity to the probe or may be provided with a plate electrode to provide a capacitive sensor with a sensitive capacitive response to the field strength relative to the shield ground. The magnitude of the signal described above is such that a high input impedance device with a well-characterized electrometer is used. As a detector for the output signal, those disclosed in US Pat. No. 37, No. 21, US Pat. On the other hand, in order to make the effective output signal larger than that of an uncharged probe, the degree of amplification must be made considerably smaller. The present invention enables highly sensitive detection of particles and gaseous media contained in environmental products such as combustion.

Embodiments of the invention will be described below with reference to the accompanying drawings.

In FIGS. 1-2, a detection probe 1 has a supporting metal substrate 2 and opposing surfaces 3 and 4, only one of which is a detection reaction surface. An external support housing or case with a pair of grounded cup-shaped perforated plates or electrodes 6 and 7 defines a free space between the probe 1 and the shield.
The pores 8 allow virtually free communication of this free space with the surrounding environment and thus contact with the surface 3. The probe 1 of FIG. 1 has a reactive surface 3-4, which may be a coating or a thin film-like material fixed by an adhesive 9 such as FEP or PFA Teflon, silicone adhesive, etc., to a metal substrate 2, which is a conductive material. It is stuck to.

The post or bolt 11 provides a support for the probe 1 and can serve as a circuit connector. The high input impedance detector and processing circuit 12 of FIG. 2 is preferably used to send an appropriate output to an alarm circuit 13 or the like. Each surface 3 and 4 is an electrical element which is an insulating or dielectric material in a charged state creating a permanent electric field.

This electric field is caused by the alignment of electrical dipoles or by the presence of excess charge within or on the dielectric material. An electrostatic analogy to a permanent magnet is possible, except that the polarization mechanism is more diverse than for magnetic materials in that this mysterious electrical material can itself contain both electrical dipoles or monopoles. . Charge retention by the dielectric element is extremely important since the lifetime of the dielectric element is a function of its charge retention ability. The fundamental property of an electrical material that governs this charge retention ability is its electrical resistivity. Generally speaking, the material must have high volume and surface resistivity in order to retain charge for long periods of time. The volume resistivity should be greater than 1.times.1 and 2 ohms/ground at 50% RH (relative humidity) and the surface resistivity should be greater than 1.times.1 and 2 ohms/ground at 50% RH. The preferred volume resistivity is 1
The surface resistivity exceeds 1×1 and 5 ohms, respectively. Practical requirements require a low weight-based water absorption (less than 1% at 95% RH) when exposed for 24 hours under relative humidity up to 95% RH.

It is desirable that the surface energy component of this dielectric element material is mainly based on the 4th scale of the contribution from the dipole-hydrogen bonding force, that is, the dispersion bonding force with the least amount of polar groups on the surface. It is desirable that the value of h/s is smaller than 5.0 ergs/sec. Representative materials include polytetrafluoroethylene (Teflon TFE), polystyrene, and polyethylene. Other examples include fluorinated ethylene propylene copolymer (FEP), perfluoroalkoxy resin (Teflon PFA), ionomer resin, and polypropylene. Still other insulating or yielding materials that can become charged and then retain this charge are also used. The sensing mechanism is essentially doubled; the dielectric material acts as an adsorbent, like an uncharged dielectric sensor, and performs an electrostatic sensing reaction.

This element differs from a simple adsorbent in that its detection performance is also dependent on electrostatic Coulomb attraction. The electric field associated with the device material amplifies the adsorption and charge sensing phenomena associated with the uncharged, non-charged material.

The amplification of adsorption performance in the uncharged state by the above device is thought to be based on the fact that the action of the electric field associated with this device aligns the adsorbed polar gas molecules, thereby increasing the effect of the conducting electric field. . This electric field also has the ability to attract charged aerosols, ionic groups, and polar gas molecules. The degree of attraction associated with the polar gas molecules present in the free space of the sensor depends, of course, on the degree of Coulomb force.
This Coulomb force can be greater than the thermal energy associated with polar gases. In the second electrostatic detection reaction described above, as shown in FIGS. 3 and 4, when the products are different, the response of the detection probe changes significantly.

Figures 3 and 4 each consist of two graphs, of which Curve A shows the response of each test sample to a smoked cotton wick inserted into a smoke chamber manufactured by Underwriter Laboratories (UL), USA. curves 15 and 16 of similar response obfuscation when viewed.

Curve B is the probe response or signal characteristic curve 17,1
It is 8. An initial pulse 21 followed by a long ramp function signal appears in the curve for the charged dielectric probe. This ramp signal 22 reaches a constant value 22a. As a result, it may continue to increase if the amplifier is saturated. Conversely, for an uncharged probe, the initial pulse 23
The output signal portion 2 remains virtually constant and approximately decreases after .
4 appears. It can be seen that a charged dielectric with an enhancement electric field due to adsorption thus has an electric field that sustains a continuous response, giving rise to distinctly different sensitivity characteristics. This charged dielectric allows detection of a wide spectrum of products produced by combustion air pollutants, including a variety of toxic and non-hazardous polar gases and charged particles. A dielectric detection probe with such continuous sensitivity characteristics can detect the combustion state even in a smoldering state. When the gutter gas is adsorbed on the surface of the detection element in an amplified manner, the amount of charge induced on the detection surface of the element increases.

To sense and measure this charge, a high input impedance detection circuit with good electrometer characteristics is generally required. On the other hand, the gain of this amplifier is much smaller than that of a non-electromagnetic adsorbent sensor. As a result, the complexity and manufacturing cost of the dielectric sensing circuit is significantly reduced. Generally speaking, the output signal detection units disclosed in the aforementioned US patents can be used with the present invention with satisfactory results. Various techniques known in the art may be used to form dielectric elements.

Using classic thermoelectric methods, a strong electric field is applied to a heated insulator, which is then cooled to align the dipoles. Dipoles can also be formed by compressing or stretching a suitable ferroelectric material. Charge injection can also be performed with a corona discharge or an electron beam. Preferably, the dielectric element is shielded from ions by being enclosed in an enclosure such as that formed by the illustrated grounding shield member.

Charge-injected dielectric elements can be made to last hundreds of years with proper shielding, making them useful where long-life use is required. The present invention makes it possible to obtain significant benefits by using dielectric materials in a charged state, such that signal changes are enhanced as a result of the interaction of contaminant components with the electric field produced by the charged material.

As previously mentioned, the shielding element 6 may be placed in close proximity to the blown unit 1 to form a capacitor-type sensor for detecting environmental components such as combustion products.

Capacitor type sensors can be used in unique configurations as shown in Figure 5. In FIG. 5, the capacitor plate 2 is a separate body and has a different potential than the blow bleed wire 26.
5 is arranged close to the blowing unit, in particular to the detection surface 4.

This plate 25 includes connecting struts which can also be supports.
Plate 25 may also be connected to ground potential or other reference potential.

FIG. 5 shows a parallel plate capacitor, although other capacitive shapes can be made to define the free space between the dielectric element sensing surface 4 and the capacitor plate 25. FIG. The configuration of FIG. 5 forms an additional detection mechanism for non-capacitive probe detection systems. An adsorption response at the detection surface 4 and a response based on the generation of multiple layers or generation layers of charge of the gas molecules on the surface 4 also occur in the configuration of FIG. According to the example of FIG. 5, the sensor has one side of the capacitor connected to the aforementioned dipole. This added plate 25 becomes a counter plate of the capacitor. Therefore, even if the electrode plate 25 is connected to the lead wire 26, a circuit is defined that affects the voltage of the lead wire 26 as a capacitor plate that changes the charge distribution within the capacitor unit. This constitutes a circuit whose capacitance characteristics change as a whole. Furthermore, the shape of the capacitor generates a strong electric field that is large enough to interact not only with uncharged gas molecules but also with a specific substance in the bonito, creating an induced dipole moment in this specific substance and gas molecules. Occur. Due to this strong electric field, the positive and negative charges in molecules and particles are separated and have dual directions. By placing the plate-like elements of the sensor in close proximity to each other to form a capacitor-type sensor, the electric field strength is increased to a level that produces effective and operable induced polarization in the particulate material. As an example, at typical operating levels, the transfer box element will be approximately 476 volts/typical (3000
volts per square inch) is developed approximately 3.2 ribs (one-eighth inch) away from the blob, which causes a significant electric field increase and dipole motion due to induction in the particulate matter and gas molecules. It will end. As mentioned above, an improvement in response can be expected by charging the sensor to a significant level, and this is particularly noticeable when the electric field strength of the sensing capacitor reaches, for example, 3150 x 1 Pivolt/M. I know that. When smoke enters the electric field, it is polarized and generates positive and negative induced charges of equal magnitude.

In this process, the electrons in the smoke deviate from their equilibrium state and generate a dipole P-Nqd due to induced polarization. This induced smoke charge appears in such a way that the resulting electric field Es of the dielectric element opposes the electric field Eo of the capacitor. The resulting capacitor electric field E is the sum of Eo and Es, except that the polarization of the induced smoke tends to weaken the original external electric field of the capacitor and is thereby reduced.
It has the same gutter properties as Eo. A weakening of the electric field of a capacitor itself indicates a reduction in the potential difference between the plates of the capacitor. Here, when the voltage is V, E is the electric field strength, and d is the distance, it becomes V-Ed. As shown in FIG. 6, the response of the capacitor type sensor is shown as a continuously increasing ramp. The motion of the dipoles due to the yield in the gas molecules and particles thus serves to smooth out the characteristics of the curve 27 and thus prevents a subsequent drop in the power of detecting the initial smoke charge 28 (Figure 6). . The yield polarization of molecules in bonito can also be described in the light of their structure.

In the absence of an external electric field, the electrical shape of the molecule is normal. When in the electric field of a capacitor, the electrical shape of the electron cloud shifts to a modified polar shape. This shift occurs so that a stable equilibrium exists between the force on the electron cloud due to the electric field of the charged plate and the force on the electron cloud due to the Coulomb force between the charges. FE here
=Fc (Formula 1)F8=NqE
(Formula 2) FC = Crocodile device 3 (Formula 3
), then NqE = 4 (Formula 4) 4 Teigosawa Sasa = Nqd (Formula 5), then the dipole moment of the molecule is therefore written as follows:
P=Nqd=4m groove 3E=EQ (Formula 6) Here, Q=4 groove 3 (Formula 7) is the electronic polarizability of the molecule.

This polarizability Q appears to depend on the radius R of the molecule rather than on the number N' of charges on the molecule. Therefore, by controlling the magnitude of the electric field, the size of the particles to be detected can be selectively adjusted. The dipole moment can be considered to be proportional to the strength of the capacitor electric field. The above phenomenon, including the polarization mechanism, can also be explained as a change in the relative yield rate of the capacitor.

As the smoke passes, it forms a dielectric between the polar slopes of the charged capacitor and causes a change in the relative dielectric constant of the capacitor. This change in yield rate causes a change in the electric field strength between the plates of the capacitor and therefore in the voltage therebetween. When there is no smoke on the dielectric surface, it can be expressed from Gauss' theorem as follows: where S = sensitivity of smoke D = exposure density of capacitor A = area of capacitor O = permittivity of dielectric Go r = Relative permittivity of dielectric E = Electric field strength of capacitor V = Voltage of capacitor d = Distance between capacitor plates Qc = Qo = Goo JE・Matsu = GooEoA (Formula 8)
Q (Formula 9) Ec = Eo = X If smoke exists on the dielectric surface, Qc = Qo - QFgo JE・ds = Gozabu (Formula 10)
Q - Qi (Formula 11) Ec = Rokufu dooAashikan EC + Gei (Formula 12) D = 'nin c + Pi (Formula 13) Here D = Q.

/A is Kasumi density E=V/d is electric field strength PFQi/A is polarization due to concession.

on the other hand, D = Do.

Since (Equation 14), D
= Go.

Go rE=do. E0Pi (Formula 15) Pi=go.
(Dor-1) E (Equation 16) or The Ten (Equation 17) Since smoke detection is performed by induced polarization in the capacitor electric field, the particle and droplet sensitivity of the detector is proportional to the charge on the surface of the capacitor. .

S QC NiQ.

-Qi Ni DA Nigo. ErEA=Go. ^． ￥． A (
Equation 18) A feature of the present invention is that a fairly large area of uniformly charged dielectric material is exposed to the gaseous products and combined with means for detecting changes in its charging status.

If this area becomes large, it is also possible to distribute several sensing units over the entire surface and to connect these to a signal processing circuit or to a separate processing circuit.

The present invention further promotes the use of non-conductive sensors in long-life, reliable and relatively inexpensive units, with applications where environmental pollutants or smoke interact with charged surface elements. Any material that causes a change in surface charge can be used.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view of a detection probe according to the present invention;
Figure 2 is a block diagram of a fire detector equipped with the probe shown in Figure 1, Figure 3 is a graph showing the sensitivity of a charged dielectric to gas molecules, and Figure 4 is a graph showing the sensitivity of a charged dielectric to gas molecules.
FIG. 5 is a probe according to the invention in a capacitor type sensor; FIG. 6 is a graph similar to FIG. 3 or 4 corresponding to FIG. 5; 1...detection probe, 2...electrode plate, 3
, 4... Reaction surface, 5... Housing or case, 6, 7... Electrode or perforated plate, 8...
...Porous plate, 9...Adhesive layer, 11...
. . . Support or bolt, 12 . . . Signal processing circuit, 13 . . . Alarm circuit. FIG. l FIG. 2 FIG. 3 FIG4 FIG. 5 FIG. 6

Claims (1)

[Scope of Claims] 1. A detection probe comprising a detection surface exposed in free space contact with an environment in which gaseous products are generated, and a detection probe connected to the detection surface and connecting the potential of the surface to an output means to prevent environmental contamination. A method for detecting environmental gas products using an electrical signal lead for generating an electrical signal in response to the presence of an object, the detection surface being connected to a charged dielectric wire for generating a charge-enhancing electric field. The volume resistivity of the dielectric material is greater than 1 x 10^12 ohm-cm at 50% relative humidity and the water absorption is less than 1% by weight at 95% relative humidity, and the dielectric material is The dielectric material reacts with the contaminant to provide a surface with a surface energy component that is primarily due to dispersive bonding forces with minimal contribution of dipole-hydrogen bonding forces, and the dielectric material reacts with the contaminant to generate detectable energy associated with contaminant products in the environment. The above detection method is characterized in that it generates an electrical output. 2. The method of claim 1, wherein the dielectric material includes an electrical monopole that shapes the charge. 3. The method of claim 1 or 2, wherein the dielectric material includes aligned dipoles forming the charge. 4 The above dielectric material is partially or entirely made of polytetrafluoroethylene (TFE), perfluoroalkoxy resin (PFA).
), fluorinated ethylene propylene (FEP), polystyrene, polyethylene, polypropylene, and an ionomer resin. 5. The method according to any one of 1 to 4 above, wherein the dielectric material has a surface charge that generates an electric field on the detection surface. 6. The method according to any one of 1 to 5 above, wherein the dielectric material has a trap type charge that generates an electric field on the detection surface. 7. A capacitive detection device for detecting the presence of environmental pollution products, the capacitive detection unit comprising a pair of capacitive electrode means separated by a non-conductive free space between them; At least one has a charged dielectric material spaced apart from the opposing electrode and forming a free surface to which an electric field is applied, the dielectric material having a volume resistivity of 5 % relative humidity.
The surface of the dielectric material is made of a material having a charge greater than 1 x 10^2 ohm-cm at 0% relative humidity and less than 1% by weight at 95% relative humidity, and which generates an electric field for charge enhancement. has a surface energy component primarily due to dispersive bonding forces with minimal contribution of dipole-hydrogen bonding forces, and the dielectric material interacts with contamination products to alter the electrical output of the capacitive sensing means. said detection device, characterized in that said detection device comprises an amplification means having a high input impedance means connected to said capacitive detection means for generating an amplified output thereof; . 8. The device of claim 7, wherein said dielectric material has an electrical monopole that generates said charge. 9. The device of claim 7 or 8, wherein said dielectric material has aligned dipoles that generate said charge. 10 The above dielectric material is partially or entirely made of polytetrafluoroethylene (TFE), perfluoroalkoxy resin (P
10. The device according to any one of 7 to 9 above, which is selected from FA), fluorinated ethylene propylene (FEP), polystyrene, polyethylene, polypropylene, and ionomer resins. 11. The device according to any one of 7 to 10 above, wherein the dielectric material has a surface charge that produces an electric field on the detection surface. 12. The device according to any one of 7 to 11 above, wherein the dielectric material has a trap type charge that produces an electric field on the detection surface. 13 The other of said electrode means comprises a grounded electrically conductive member surrounding one of the electrode means, said member being porous to allow relatively free movement between said electrode means and contact with said active material. 13. The device according to any one of 7 to 12 above, wherein the one electrode means is housed in the other electrode means and the dielectric material is provided on opposite surfaces thereof. 14 The electric field strength of the above capacitor is at least 3150
14. The device according to any one of 7 to 13 above, wherein the voltage is 10^5 volts/m. 15. The device according to any one of 7 to 14 above, wherein the electrode means is a plurality of plates, and these plates are surrounded by an outer shield earthing means. 16. The device according to 15 above, wherein the capacitor plates are connected to each other and to the input side of the amplifying means. 17 Above 15 where one capacitor plate is grounded
The device described.